Non-Isothermal Crystallization of Polymer Nanocomposites Based on Polycarbonate Filled With Carbon Nanotubes

The article is devoted to theoretical and experimental studies of the dependence of the heat of crystallization of polymer nanocomposites on such factors as the mass fraction of the filler and the cooling rate of composites from the melt. Enthalpy relaxation in the cooling runs was monitored with the temperature-modulated DSC instrument (Perkin Elmer DSC-2 upgraded and supplied with signal processing software by the IFA GmbH, Ulm). Each sample was initially “overheated” by ~ 25 K above the apparent melting temperature of PP (Tm ≈ 490 K), stored for 3 min. and cooled in the standard DSC mode to ~ 360 K at one of the six available constant cooling rates q¯ (from 20 K/min down to 1 K/min). Studies of non-isothermal crystallization of polycarbonate and nanocomposites containing from 0 to 5 wt.% of carbon nanotubes have been conducted. It was established that the value of the heat of crystallization of nanocomposites significantly decreases with an increase in their cooling rate and an increase in the mass fraction of the filler. It is shown that the crystallization for polymer nanocomposites has the assumption of a superposition of intravenous initial (unimpeded) and secondary (limited) mechanisms of crystal formation, respectively.